Feb. 18, 2011 (Orlando) -- Thousands of men with low-risk prostate cancer are having unnecessary and expensive imaging tests, while thousands of men with high-risk disease who should get the tests are not.

When men are diagnosed with prostate cancer, they are classified as low-, intermediate-, or high-risk depending on their life expectancy, overall health status, and tumor characteristics. Current guidelines state that only high-risk men should undergo CT, MRI, and bone scans to determine if their cancer has spread beyond the prostate.

But in a study of more than 30,000 men diagnosed with prostate cancer in 2004 and 2005 in the U.S., 36% of low-risk men and 49% of intermediate-risk men got the scans.

"The chances of finding disease outside the prostate in these patients on one of these scans is less than 1%," says study leader Sandip Prasad, MD, urologic oncology fellow at the University of Chicago.

Although those tests may expose men to unnecessary radiation and use resources unnecessarily, the bigger concern is that 39% of men with high-risk disease who should have undergone imaging did not, he tells WebMD.

The findings were presented at the Genitourinary Cancers Symposium.

Misuse of Tests May Lead to Wrong Treatment

"This is a double whammy," says Mack Roach III, MD, head of radiation oncology at the University of California, San Francisco.

"This is a perfect example of how we are wasting money on inappropriate tests and then denying other people appropriate care," he tells WebMD.

Misuse of the tests can lead to the wrong treatment, Roach says.

"If the scans show cancer has spread in high-risk patients, there is no sense in the patient having his prostate taken out. He'll need chemotherapy and hormone therapy," he says.

"In a low- or intermediate-risk patient, on the other hand, any sign of [cancer spread] is likely a false-positive test. But the patient may be denied [surgery] because of the results," Roach says.

Prasad says he believes patients and doctors both contribute to the high rates of unnecessary tests.

"Men may ask for it. Physicians may do it because it gives them reassurance that they haven't missed anything," he says.

Prasad says the unnecessary tests cost taxpayers more than $35 million -- "more than 10% of the annual budget of the National Cancer Institute for prostate cancer research."

The study included 9,640 men with low-risk prostate cancer, 12,966 men with intermediate-risk prostate cancer, and 7,577 men with high-risk prostate cancer.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.